The research objectives for the coming year are: 1. To confirm that the AMV provirus integrates in tandem with the endogenous provirus in leukemic chicken cells induced by AMV. This will be done by analysis of proviral DNA fragments generated by treatment of leukemic cell DNA with restriction endonucleases. 2. To determine whether AMV proviral DNA integrates in a similar manner in cells from different tissues. 3. To determine whether the provirus of transforming oncornaviruses, e.g., Rous sarcoma virus and of non-transforming oncornaviruses, e.g., Rous associated virus, integrates in a manner similar to that of the AMV provirus. 4. To further characterize the viral genome. BIBLIOGRAPHIC REFERENCES: Dastoor, M. N.., Shoyab, M. and Baluda, M. A. Variations in integration site of avian oncornaviruses in different hosts. J. Virol. 21: 541-547 (1977). Evans, R. M., Shoyab, M., Drohan, W. N. and Baluda, M. A. Homogeneity and complexity of avian oncornavirus proviral DNA determined by molecular hybridization. J. Virol. 21: (1977).